About The Heat Exchanger LMTD Calculator

The Heat Exchanger LMTD Calculator computes terminal temperature differences and logarithmic mean temperature difference for parallel-flow or counter-flow arrangements. It is useful for quick heat exchanger sizing checks.

How to Use the Heat Exchanger LMTD Calculator Online

1. Enter the required inputs in the fields above using the units shown on the labels.
2. Select any mode, shape, or method options so the calculation matches your scenario.
3. Run the calculation and review the result summary in the output panel.
4. Check the units, assumptions, and project requirements before using the result outside preliminary review.

Choosing Options Correctly

Temperatures can be in Celsius or any consistent temperature scale for differences. The selected arrangement must keep both terminal temperature differences positive.

Common Use Cases

• Calculate LMTD from hot and cold stream inlet/outlet temperatures.
• Compare parallel and counter-flow temperature driving force.
• Check heat exchanger assumptions before UA or area calculations.

Quick FAQ

What is LMTD?
Log mean temperature difference is an effective temperature difference for heat exchanger calculations.

When does LMTD fail?
If terminal temperature differences are zero, negative, or physically inconsistent, the setup is not valid for a simple LMTD calculation.

Does it size a full heat exchanger?
No. Area sizing also needs heat duty, overall U value, fouling, correction factors, and flow arrangement.

Why does counterflow often give a higher LMTD?
Counterflow can maintain a more useful temperature difference along the exchanger length.